`{:(E_(M^(2+)//M)^(@),Cr,Mn, Fe, Co, Ni, Cu),(,-0.91,-1.18,-0.44,-0.28,-0.25,+0.34):}`
From the given data of `E^(@)` values, answer the following questions :
(i) Why is `E_((Cu^(2+)//Cu))^(@)` value exceptionally positive ?
(ii) Why is `E_((M^(2+)//M))^(@)` vlue highly negative as compared to other elements ?
(iii) Which is a stronger reducing agent , `Cr^(2+)` or `Fe^(2+)` ? Give reason.

Explanation

(i) This is due to the reason that `Cu^(2+)` ion has high value of `Delta_(a)H^(@)` and low `Delta_(hy)H^(@)`.
(ii) This is due to the reason that `Mn^(2+)(3d^(5))` configuration is exceptionally stable.
(iii) `Cr^(2+)` is a stronger reducing agent because of +3 oxidation state of Cr ( `t_(2g)^(3)` orbital) is more stable.